For many years it has been a common medical-surgical technique in the treatment of malignant tumors to inject radioactive seeds in the tumor that will provide radiation from the seeds. These seeds are small tubular sections filled with a radioactive material and sealed at each end. These seeds may be of any convenient size although they are frequently not more than one millimeter in diameter and 3-4 millimeters in length. The number and positioning of the seeds in the tissue depends upon the treatment considered most appropriate by the physician.
The devices for accomplishing these implantation treatments have varied considerably. One type which was used in the first of such treatments is shown in U.S. Pat. No. 2,269,963 having the appearance of a hand gun with a plunger along the barrel of the gun to advance and deposit seeds from the forward end of the device. Other more recent devices are seen in U.S. Pat. Nos. 3,921,632; 4,086,914; and 4,167,179.
These techniques involving guns or needles for implanting such seeds have proved to be deficient in many respects, particularly because they do not provide a means for implanting seeds at a precise spacing and location to perform the desired treatment. These deficiencies led me to seek other devices and methods by which the seeds could be located in a fixed spaced relationship to each other. One method I developed involved the use of a suture containing the seeds in a fixed spaced relationship. After the suture was threaded into the tissue the suture would be absorbed naturally in the human body, leaving the seeds in a fixed spaced relationship. The same basic idea was employed using a needle to inject seeds separated by absorbable spacers. My techniques were reported in the following articles:
The American Journal Roentgenology, Radium Therapy, And Nuclear Medicine, Vol. CXIV, No. 3 March, 1972, Pages 620-622. PA0 Radiology Vol. 105, No. 2, November 1972, Pages 454-455 PA0 Radiology Vol. 117, No. 3, December 1975, Pages 734-735 PA0 Surgery, Gynecology & Obstetrics, Vol. 1 or 2 May, 1976, Pages 667-670.
A more recent development of mine is a sheathed needle injection device which is loaded with 1-5 seeds without any absorbable spacer material, the sheathed needle is injected into the tissue, the seeds are ejected from the needle through slots in the sheath, and the sheathed needle is then withdrawn leaving the seeds in the tissue. This technique is described in Radiology, Vol. 122, No. 3, March 1977, Pages 832, 834. While this reported device is a vast improvement over previous techniques it, also lacked some precision in positioning the seeds because the method of ejecting seeds from the needle functioned imperfectly. Accordingly I have developed the device of this invention as a new and improved injector for implanting radioactive seeds in human tissue with precision.